Osage River, one of the historic water-courses of eastern Kansas, has its source in the southern part of Wabaunsee county. It flows eastward through Osage and Franklin counties into Miami, where it changes its course toward the southeast and crosses the state line near the center of Linn county. From there it continues eastward through the counties of Bates, St. Clair, Benton, Camden and Miller, in the State of Missouri, and finally, empties into the Missouri river a few miles below Jefferson City. In high water it is navigable for small boats for a distance of about 200 miles. Its upper course is sometimes called the Marais des Cygnes, along whose banks were enacted some of the most tragic events of the "Border War."